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In this April 15, 2009 file photo, an unidentified worker steps through the maze of hoses being used at a remote fracking site being run by Halliburton for natural-gas producer Williams in Rulison, Colo. The U.S. Environmental Protection Agency said, for the first time, on Thursday Dec. 8, 2011, that a controversial method of improving the productivity of oil and gas wells in causing groundwater pollution and contaminating water wells., commonly called fracking. Photo by DAVID ZALUBOWSKI, THE ASSOCIATED PRESS FILE